In my experience, sand sleepers or mucus sleepers don’t succumb to infection from ich like cave dwellings wrasse or in general other fish species do. Part of this is to do with the way that marine ich (or cryptocaryon irritans) reproduces in the water column. The parasite is free floating in the water column and the phases of reproduction occur at night when the originally described wrasses are asleep. The initially described sand sleepers and mucus sleepers are effectively protected from this opportunity for infection. If your fish is still eating, that’s a great sign. Consider treating the food with vitamins and you may be able to keep it in your tank waiting out the infection before you add more fish.
I’ve had ich outbreaks before and my moyeri leopard wrasse (another sand sleeper) never displayed telltale signs of infection nor any white spots. Meanwhile other fish succumbed to the illness.
Hope your wrasse pulls through!
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